Automatic transmission solenoid valve like a faucet, different degrees of opening through the hydraulic oil flow is different, the resulting pressure is different. The solenoid valve is controlled by the transmission control module TCU, which is basically neutral and the pressure in the gear is constant, except that the opening of the solenoid valve is adjusted during the gearshift to improve gear ride comfort. Different solenoid valves control different clutches or brakes and play a role in different gears. Each gear is controlled by one or several solenoid valves.
Automatic transmission solenoid valve roughly divided into two categories
Through a certain current or voltage, so that the battery valve internal coil power, and then drive the internal needle valve or
Displacement, or block the passage or open the oil. Used to control the shift.
Current duty cycle control, through the frequency control. Used to adjust the oil pressure.
Solenoid valve can not be in the absence of oil pressure in the case of idling, because it will be more likely to cause the solenoid valve dry burn damage.
The inspection of the solenoid valve can be divided into three types
1, static check static check is the ignition switch OFF, measuring the resistance of the solenoid valve, as shown in the figure, with a multimeter pen tip and solenoid valve pin connected to observe the instrument screen display resistance, if greater than the rated value , Indicating that the solenoid valve coil aging; if less than the rated value of the coil turns between the short circuit; if infinite, indicating the solenoid valve coil open, these conditions that the solenoid valve has failed, must be replaced.
2 dynamic inspection Dynamic inspection refers to the actual working process of the analog solenoid valve, with a certain amount of pressure instead of oil pressure, through the electromagnetic valve constantly artificial incentives to check the solenoid valve spool movement is smooth, the seal is good. With a gas gun will be a certain pressure through the cone rubber head applied to the solenoid valve in the working oil hole, press the control switch so that the solenoid valve repeatedly off and observe the flow of air flow at the drain changes, if the air is always present, Valve seal is bad; if there is no air flow, indicating that the solenoid valve plugged stuck; if the air flow off the line is not standardized, indicating the solenoid valve occasional stuck; if the air with the solenoid valve action changes, indicating normal solenoid valve.
3, hot check the first two checks, and can not be 100% of the problem, a large number of maintenance examples have proved that some of the solenoid valve in the first two checks are normal circumstances, into the heat conditions are abnormal, It is difficult to create some of the trouble to make maintenance work in a strange fault phenomenon. As the name suggests, thermal check is to simulate the normal operation of the automatic transmission can reach the set temperature, with a hot air or other oil, electricity and other heating equipment, man-made to the solenoid valve to its normal operating temperature, and then its Resistance and dynamic pressure test, then check the results if normal, indicating that the solenoid valve is no problem; if the performance is abnormal, it must be replaced.